Biomarkers, Creatine Kinase, and Kidney Function of Special Operation Candidates During Intense Physiological Training.

INTRODUCTION: The purpose of this pilot study was to assess for biomarkers indicative of passing intense physical training and establishing normative values within the tactical athlete population. Unfortunately, none of the biomarkers assessed were indicative of passing training, however, glucose, blood urea nitrogen, and creatine kinase (CK) levels stood out as abnormal. CK levels are commonly used in conjunction with muscle pain and/or myoglobinurea to diagnose exertional rhabdomyolysis (ER) in athletes and the military population. However, research shows that high CK levels may not correlate with acute kidney failure in ER. MATERIALS AND METHODS: After IRB approval and informed consent, blood samples were obtained from 21 volunteers during two phases of the combat control training pipeline: the first phase (12 participants) was 2 hours of daily physical training followed by 8 hours of academics, and the second phase (nine volunteers) a grueling, 72 hour, intense training cycle (stress inoculation training, SIT) with a historic pass rate of only 50%. Biomarkers were also tracked 48 hours after cessation of SIT. RESULTS: None of the biomarkers assessed showed a correlation with passing SIT, but high CK levels were well above the diagnostic threshold for ER-as high as 28,000 u/L. At a single point in time, a significant correlation did not exist between CK and others markers associated with rhabdomyolysis. Across time, partial correlations controlling for subject did exist between CK and other markers. CONCLUSIONS: In our low-powered case control study (pilot study), a nonpathologic elevation of CK is prevalent in high-intensity military training, but not shown to correlate with values associated with acute kidney injury. We assume that real-time collection of these markers could be used once sensors are capable of real-time collection and have the potential for diagnostic affordance. When measured in a between subjects design, our study showed a lack of significance when correlating markers of acute renal injury and elevation of CK. However, when utilized for tracking purposes (within subjects design), the results do show a positive correlation between CK and renal failure biomarkers-specifically only at high physiological stress points.

Interactions of sex and aging on spatiotemporal metrics in non-pathological gait: a descriptive meta-analysis.

BACKGROUND: Individual studies examining aging-related changes in gait offer conflicting information on differences between male and female spatiotemporal metrics over the course of a mature lifetime. Furthermore, these studies do not often account for a known difference in size between men and women, and thus may reach conclusions based upon size rather than sex differences. OBJECTIVE: To examine the influences of sex, height, and age on spatiotemporal metrics during non-pathological gait over the course of adult aging. DATA SOURCES: Potentially relevant articles were identified from PubMed, Web of Science, and Google Scholar using the key words 'gait,' 'walk', 'gender,' 'sex,' 'female,' 'male,' 'gait speed,' 'step length,' and 'cadence.' ELIGIBILITY CRITERIA: (1) article could be obtained in English, (2) contained information about non-pathological subjects, (3) analyzed kinematics of walking, (4) provided female and male data, (5) average female/male age difference not more than 5 years, (6) reported a measure of variance and number of subjects, and (7) no known retractions associated with the publication. RESULTS AND CONCLUSIONS: Non-dimensional gait speed analysis suggests that gait speed differences between men and women may be an artifact of size rather than sex. In both raw and dimensionless data, this analysis indicates that men may take longer step lengths than women, and women may have a higher cadence than men. This analysis also identified a possible increase in many metrics between 20 and 40 years of age, before decreasing around the fifth decade of life. Future studies should examine these trends across the entire lifespan.

Acceleration of image analyst training with transcranial direct current stimulation.

Humans today are routinely and increasingly presented with vast quantities of data that challenge their capacity for efficient processing. To restore the balance between man and machine, it is worthwhile to explore new methods for enhancing or accelerating this capacity. This study was designed to investigate the efficacy of transcranial DC stimulation (tDCS) to reduce training time and increase proficiency in spatial recognition using a simulated synthetic aperture radar (SAR) task. Twenty-seven Air Force active duty members volunteered to participate in the study. Each participant was assigned to 1 of 3 stimulation groups and received two, 90-min training sessions on a target search and identification task using SAR imagery followed by a test. The tDCS anode was applied to site F10 according to the 10-20 electroencephalographic electrode convention while the cathode was placed on the contralateral bicep. Group 1 received anodal tDCS at 2 mA for 30 min in the first training session and sham tDCS in the second session. Group 2 received the stimulation conditions in the opposite order. Group 3 did not receive stimulation at all. Results showed that participants receiving training plus tDCS attained visual search accuracies ~25% higher than those provided with sham stimulation or no stimulation. However, a corresponding performance improvement was not found in the first training session for the change detection portion of the task. This indicates that experience with the imagery is important in the tDCS-elicited performance improvements in change detection.

Analysis of algorithms predicting blood:air and tissue:blood partition coefficients from solvent partition coefficients for prevalent components of JP-8 jet fuel.

Algorithms predicting tissue and blood partition coefficients (PCs) from solvent properties were compared to assess their usefulness in a petroleum mixture physiologically based pharmacokinetic/pharmacodynamic model. Measured blood:air and tissue:blood PCs for rat and human tissues were sought from literature resources for 14 prevalent jet fuel (JP-8) components. Average experimental PCs were compared with predicted PCs calculated using algorithms from 9 published sources. Algorithms chosen used solvent PCs (octanol:water, saline or water:air, oil:air coefficients) due to the relative accessibility of these parameters. Tissue:blood PCs were calculated from ratios of predicted tissue:air and experimental blood:air values (PCEB). Of the 231 calculated values, 27% performed within +/- 20% of the experimental PC values. Physiologically based equations (based on water and lipid components of a tissue type) did not perform as well as empirical equations (derived from linear regression of experimental PC data) and hybrid equations (physiological parameters and empirical factors combined) for the jet fuel components. The major limitation encountered in this analysis was the lack of experimental data for the selected JP-8 constituents. PCEB values were compared with tissue:blood PCs calculated from ratios of predicted tissue:air and predicted blood:air values (PCPB). Overall, 68% of PCEB values had smaller absolute % errors than PCPB values. If calculated PC values must be used in models, a comparison of experimental and predicted PCs for chemically similar compounds would estimate the expected error level in calculated values.